Assessment of nutritional and phytochemical quality of Dawadawa (an African fermented condiment) produced from Bambara groundnut (Vigna subterranea)

This study investigated the nutritional composition, antinutrients and phenolic composition of raw, hulled and dehulled Bambara groundnuts (BGN) (Vigna subterranea) and their derived dawadawa products. Phenolic compounds were investigated using ultra-high performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UHPLC/Q-TOF-MS) system while determination of amino acids and mineral contents were done using high performance liquid chromatography (HPLC) and inductively coupled plasma optical emission spectrometry (ICP-OES), respectively. Oxalate, tannin and phytic acids were quantified while microstructure of the samples was viewed using scanning electron microscopy (SEM). Results showed a decrease in quinic acid, medioresinol and quercetin-3-O-galactoside-7-O-rhamnoside in all dawadawa samples. Likewise, significant (p ≤ 0.05) increases were observed for protein, majority of the amino acids and minerals after fermentation. On the contrary, levels of oxalate, tannin and phytic acids were noted to have decreased in the dawadawa samples, as compared to the BGN. SEM also revealed modifications in the structural morphology of the samples. The higher phenolic compounds in the hulled dawadawa, positions it as an excellent source of health beneficial components, while the dehulled samples could be equally considered from a nutritional perspective.